MechChem Africa April 2019

Mech Chem APRIL 2019 AFRICA

This month: Bearing and seal design for tunnel boring

I4.0 machines benefit from automation platform

CDM’s high-efficiency diamond recovery circuit

CPO software for true energy savings

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Power transmission, bearings, bushes and seals 8 Bearing and seal design for tunnel boring machines The safe, reliable operation of tunnel boring equipment relies on the integrity of critical bearings and seals.This article from SKF describes the design considerations involved in arriving at suitable solutions.

P U B L I C A T I O N S CR O WN

10 Flexibility, innovation and tailormade drive solutions 13 Regular wear checks, better maintenance management 15 The Cross-Check Torque Seal from DYKEM Hydraulic and pneumatic systems 16 How I4.0-based machines benefit from automation platform

Published monthly by Crown Publications cc Cnr Theunis and Sovereign Streets Bedford Gardens 2007 PO Box 140, Bedfordview, 2008 Tel: +27 11 622 4770 e-mail: mechchemafrica@crown.co.za www.mechchemafricamagazine.co.za Editor: Peter Middleton e-mail: peterm@crown.co.za Assistant editor: Phila Mzamo e-mail: philam@crown.co.za Advertising: Brenda Karathanasis e-mail: brendak@crown.co.za Design: Darryl James Publisher: Karen Grant Deputy publisher: Wilhelm du Plessis Circulation: Brenda Grossmann The views expressed in this journal are not necessarily those of the publisher or the editors. P U B L I C A T I O N S CR O WN P U B L I C A T I O N S CR O WN 2015/02/10 01:17:09PM

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From the early days of Industry 4.0, Festo has been deeply engaged and has built up significant experience in research, production and process optimisation. Now an impressive automation platform enables the company’s customers to do the same. Eberhard Klotz, head of Industry 4.0 at Festo, explains. 17 Hytec appointed African service partner to ZOLLERN 19 Rand-Air oil-free compressors assist luxury vehicle manufacturer 20 BMG strengthens partnership with Eaton Hydraulics 21 Revolutionising cost and quality for a flawless spray-painting finish Automation, process control, instrumentation and CAE 22 Swerve robotic platform relies on SICK LiDAR sensor A SICK Automation LiDAR sensor was used to build a winning robotic platform in the prestigious Drexel University’s annual College of Engineering (CoE) senior project design competition. 25 SimLab slashes simulation cycle time for SMEs Petra Diamonds has installed a modern, fit-for-purpose diamond processing plant at its Cullinan Diamond Mine (CDM) that incorporates thyssenkrupp autogenous grinding (AG) mills and HPGRs (high-pressure grinding rolls) in the processing circuit. 30 BenchREMOTE monitor for Elf Drilling 32 Nanotechnology and the changing coatings industry Innovative engineering 38 CPO software for true energy savings Russell Hattingh, engineering manager for Johnson Controls Systems & Service in South Africa, talks about Central Plant Optimisation (CPO) software, which, he argues, offers better energy savings than any building management system (BMS) alone. Regulars 2 Peter’s comment: Load shedding – taking back control 4 On the cover: 80 GHz radar secures cosmetic material supply VEGA Controls’ Jürgen Skowaisa talks about replacing existing sensors with new-generation devices without having to incur the effort and expenses of new approvals. 6 SAIChE IChemE News From process engineering to quality management: MechChem Africa profiles Qasim Fakir. 34 Product and industry news 40 Back page: Tyres for autonomous shuttle service 26 Updated Studio 5000 for enhanced industrial security 27 Sandvik’s AutoMine backs mixed fleet operations Minerals processing, metallurgy and materials 28 CDM’s high-efficiency diamond recovery circuit

Transparency You Can See Average circulation October-December 2018: 5 171 Printed by: Tandym Print, Cape Town

Cover story: VEGA Controls Frikkie Streicher Tel: +27 82 564 6367 frikkie.streicher@vega.com

Publisher of the Year 2018 (Trade Publications)

April 2019 • MechChem Africa ¦ 1

Load shedding – taking back control

O ver three years ago, the United Kingdom voted to leave the European Union in a referendum; a process that has since triggered the ‘Brexit crisis’. The highly creative catch phrase used by the leave campaign in this controversial referendumwas ‘take back control’, which ‘Brexiteers’ such as Boris Johnson continue to reiterateevery time they feel their ‘hardBrexit’ prefer- ence is slipping away. They argue that UK voters in the referendum and democracy itself will be ‘betrayed’ if full control is not wrestled back from Brussels. Ironically, the UK parliament itself seems to have little control over the process and the average UK voter is unlikely ever to have any direct control over the trade deals, customs tariffs and emigration policies that are at the heart of the Brexit debate. Identifying the ‘least worst Brexit option’ is now the challenge facing the UK government and parlia- ment. With South Africa’s sixth democratic election imminent, a similar dilemma is facingus and thehopeof ‘takingback control of our country’ is as distant as ever. Load shedding has now been suspended, but Eskom’s Andrew Etzinger is warning that we are not out of the woods yet. “There is an underlying reality that things can change at short notice. That is why we do not want to declare victory,” he said. Isn’t it irrationally comforting to have him back as a spokesman, though, even if his role seems different every time he is quoted? Senior general manager: Demand Management? Acting head of generation? At the time of writing, Public Enterprises Minister Pravin Gordhan and Eskom board chair Jabu Mabuza were about to deliver a media briefing at ‘a power station 90 minutes outside of Johannesburg’ about the current status of South Africa’s electricity supply. Whatever the outcome, however, will South African people and businesses have any control over when and where they can use electricity? At a media briefing held in Pretoria on 28 March, senior energy experts from the CSIR gave scientific advice on howSouthAfricans can alleviate the impact of load shedding, “taking control of their household electricity usage and saving money at the same time”. The talk, by principal researcher of the CSIR’s Energy Centre, Jarrad Wright, and senior researcher Joanne Calitz, discussed a range of options available to reduce electricity usage in households, while also

supplying household needs during load shedding or grid outages. Wright and Calitz urged South Africans to becomemore energy efficient, change their behav- iour and make use of complementary energy sources. “Taking control of electricity in households by install- ing energy efficient devices and appliances, while also implementing alternative energy strategies, could minimise the impact of load shedding or grid outages, while also saving money,” saidWright. The detailed presentation byWright takes a prop- erly scientific view of the benefits and consequences of such choices and starts by pointing out the severity of the load shedding in February and March of 2019. Not only was it the first time in our history that Stage 4 loadshedding had to be implemented (4 000 MW), butMarch2019was ourworstmonthof loadshedding with an estimated total of 595 GWh of undeliverable demand in themonth. In addition, while loadshedding in2015affectedmostlypeakperiods, during this 2019 crisis, loadshedding occurred both day and night. Wright argues for adopting a cascade approach to minimising the risks of supply disruption: reduce demandby implementing energy efficiency initiatives; shift demand by changing time of use behaviour; re- placing electricity usewith alternative energy sources such as LPG, solar heaters, wood or charcoal; and installing one’s own electricity generation systems suchas standby generators, solar PVsystems, battery- basedbackupsupplysystemsorcombinationsofthese. He says that readily available options in combina- tion can help households as well as the power grid in different ways, and he rates each option in terms of helping to reduce grid costs, improving supply reli- ability and environmental impact. Neither Brexit in the UK nor the results of South Africa’sMay 8 election are likely to leave anyone feel- ing more in control of their destiny. Nor will knowing what is wrong with Eskom, how long it will take to fix and howmuch more it is going to cost us. But making some of the changes suggested by the CSIR, so that during load shedding and, more routinely, during peak/expensive use periods, households have alternative energy andelectricity supply options, does amount to taking back control. We should all be investing in alternative energy op- tions, for the good of the economy, for the sustainabil- ity of Eskomand, most importantly, to enable us to feel less helpless and more in control of our daily lives. q

Peter Middleton

MechChem Africa is endorsed by:

2 ¦ MechChem Africa • April 2019

80 GHz radar secures cosmetic material supply Pharmaceutical and cosmetics plants are often hesitant to replace existing sensors with different measurement devices because the effort and expense of new approvals are frequently much greater than the costs of the sensors themselves. This example from a manufacturer of special chemical substances shows that there are other ways.

Jürgen Skowaisa, Product Manager Radar, VEGA Grieshaber KG.

A lthough beauty is in the eye of the beholder, it does no harm to give people a little help for their personal well-being.With this goal in mind, the multinational company Croda Ibérica SA has been supporting renowned companies in the beauty and personal care industries through the development of its products. On one hand, the products must bemade fromhigh-quality rawmaterials that meet the high-quality demands of the end us- ers in this sector and, on the other, they must be sustainable. This includes, for example, the use of renewable energy sources as well as careful handling of natural resources, and the use of certified, sustainable palm oil. Over the past decade, numerous newskin, sun and hair care technologies have been de- veloped from natural plant-based materials. Apart from their effectiveness, the products must comply with quality assurance regula- tions and market analyses, and regulatory requirementsmust also be considered. Every cosmetic product must undergo several tests before it comes onto the market and hardly anything in an approved process may be

changed. This also applies toby-products that aremanufactured in large quantities at the site in Fogars de la Selva , a Catalonian district of Barcelona, under the name Croda Ibérica , which is responsible for the Spanish and Portuguese markets. Croda Ibérica is therefore grateful for every process and measuring point that hasworked reliably overmany years. The company has been working with VEGA Spain for more than 10 years and relies completely on the local VEGA subsidiary, which is supported with fill-level measurement technology by its specialist parent in Schiltach, Germany. The whole factory houses about 200 sensors

of different product fami- lies, including pressure

transducers, guided radar sensors, different limit detectors for liquids and solids, as well asdifferentialpressuretransducers.Aspecial feature of the measuring points is that all of the VEGA measuring instruments and sensors used are ATEX-certified. The only fill level measuring point at which a VEGA sensor is not installed is a reactor in which temperatures of more than 300 °C are typi- cal. Here, a weighing system is used instead. The VEGAPULS 64 radar fill-level measur- ing instrument, launched onto the market in 2016, is also in use at the site and demon- strates its advantages in the measurement of a mixture of special detergent recipes and alcohols. Here, the sensors measure the raw material levels in three tanks with heights of two, three and five metres. The result of the measurement is decisive for the further processesbecausetheendproductofthisraw material accounts for about a quarter of the entire factory production. Since very reliably measured values are crucial for the company, the expenses at this measuring point were always high. At first, differential pressure transducers were used but these led toaccumulationof deposits that clogged up the pipe system. The company then switched to guided radar as ameasuring principle but the structure of the tank with Radar sensor with high transmitter frequency offers advantages

On tanks for storing raw materials, the VEGAPULS 64 allows non-contact filling level measurement down to the bottom of the tank despite internal installations such as heating coils.

4 ¦ MechChem Africa • April 2019

⎪ Cover story ⎪

built-in pipes led to heavy deposits on the inserted rod probe. The medium, with its tendency to settle on the tank wall and installa-

tions, also led to inaccuracies in the previous measurements,

while the heating coils and pipework in the

reactor influenced the measuring signals. The problems at these me a s u r i ng po i n t s were only solved with the installation of the VEGAPULS 64, which operates with a high fre- quency of 80 GHz – com- pared to 26 GHz with previous generations. Because the VEGAPULS 64 mea-

sures without contact using radar tech- nology, there are automatically fewer problems with product deposits. The radar measuring technology is also ideal from a hygienicperspective,asthefront-flushencap- sulated antenna, for example, can be cleaned optimally and is insensitive to the extreme conditions of the sterilise- and clean-in-place (SIP and CIP) processes. The VEGAPULS 64 is also insensitive to deposits or formation of condensation, de- spite its shorterwavelength. This is achieved, principally, by adapting the sensitivity in the near range of the sensor. The distance- dependent dynamic adaptation reduces the influences of interferences directly in front of the antenna system and, at the same time, enables very high signal sensitivity at a greater distance. Reliable filling level mea- surement is therefore also possible during cleaning cycles. Reduction of interference signals The structure of the tank with its complex installations no longer has any influence on themeasurement. Thiswas achieved through better focusing of the radar measuring instrument, which depends on transmitter frequency and the effective antenna surface area. The three-fold higher transmitter fre- quency, however, enables smaller antenna sizes, which achieve similar signal focusing to lower frequency sensors. This enables much smaller process connections with an antenna size of just ¾-inch, no bigger than a one-Euro coin. Thenewantennaversionhelped to reduce the interference signals in the near range considerably. Since the antenna system is integrated into theprocess connection, noan- tenna protrudes into the tank, so it is possible to measure reliably right up to the process connection. The tank volume can therefore be better utilised to create more flexibility.

The narrow radar beam of the VEGAPULS 64 sensor allows it to be installed where metal elements exist.

Measurement down to the bottom of the tank Another positive aspect which turned out to be extremely important in practice has emerged. With the VEGAPULS 64, it is pos- sible to measure right down to the bottom of the tank evenwith quite different media. This isdecisiveinviewofthefactthatthetankmust be completely emptied every two weeks. Operators need to know that, with media of low relative permittivity, some of the sig- nals penetrate the medium and are reflected by the bottom of the tank. Therefore two signals are returned: the actual filling level and the bottom of the tank. The signals from the bottom are greater if the relative permit- tivity of the medium is lower, so increasing reflection from the bottom of the tank (e.g. flat metal bottom). Due to the much shorter wavelength of the 80 GHz signals of the VEGAPULS64, thesedifferences aredamped in themediummuchmore strongly than with 26 GHz sensors. The reflection from the bot- tom of the tank is therefore lower. This has the result that a media level measurement near to the bottom of the tank is much easier than with previous sensors. Fast commissioning Although the structure of the tank was com- plex, the conversion and installation of the VEGAPULS 64 was fast. Since the existing process connection could be used, the new sensor was simply installed on the available connection. The procedure has already proven ef- fective in other applications in the phar-

maceutical and cosmetics industry. Plants and apparatus have usually gone through acceptance testing, and subsequent construc- tional modifications are only possible at great expense. The VEGAPULS 64 thread sizes can beadaptedwithappropriateadapters, suchas on clamp connections. Other process connec- tionsareavailableforuseinasepticsectionsin which only PTFE is used as a medium-wetted material. These process connections meet the requirements in accordance with 3-A and EHEDG. Operation was familiar because the VEGAPULS 64 is also equipped with the provenplics ® concept.ThePLICSCOMdisplay and operating module still serves for com- missioning and operation of the sensors and indicates the measured values on site. No PC or special software is required. The display andoperatingmodulecanbeinsertedintoand removed fromthe sensor at any timewithout interrupting the power supply. Wireless bluetooth communication was also introduced last year. This is particularly interesting for places with difficult access, rugged industrial environments andEx areas. Themodule is downward-compatible and can be used for the entire installed base of the plics ® sensors – in pressure and filling level applications with 70 different instrument types – without a software update and using the same proven operating structure. In this way, the user can configure and parametrise his or her plics sensors from a safe distance with a smart phone or tablet, regardless of whether Apple or Android. Display and diag- nostic functions are also available. q

April 2019 • MechChem Africa ¦ 5

MechChemAfrica profiles Qasim FakirAMIChemE, an active SAIChE IChemE member in the Gauteng Branch, whose rich and varied career highlights the vital role chemical engineering plays in enhancing local manufacturing and product quality. From process engineering to quality management

Qasim Fakir was awarded a Sasol bur- sary for his undergraduate studies in chemi- cal engineering at the University of the Witwatersrand, whichhebegan in2004when he was 18 years old. “I found it challenging from the outset. I was from an underprivileged government school, which, I felt, left gaps in my under- standing and the problem solving strategies required to cope with the way the engineer- ing works. I was also the first member of my family to be afforded the opportunity to attend university, so I found it difficult to relate tomy family and had no rolemodels to consult about howtonavigate university life,” he tells MechChem Africa . “My time at Wits was an incredible time for me, though. I fondly remember the late nights having to work on tutorials while finding the time to balance my social and sports commitments. An avid sportsman, I played for the Wits 1 st team in Volleyball and represented Wits at numerous sports tournaments. I also remember the various teaching staff who helped shapeme, with the late Professor Donald Williams being a key individual in helping to shape my chemical

engineering knowledge,” Fakir recalls. As a condition of the Sasol bursary, stu- dents were required to work on rotation at different Sasol business units. Fakir loved the rotation side of Sasol’s bursary strat- egy as it exposed him to the opportunities available and the different roles of chemical engineers. “One of my favourite placements was at the Sastech R&Dunit, which develops new technologies and tests new approaches before scaling them up for the production environment. I wanted to work there once qualified, but after graduating with my undergraduate degree in 2008, Sasol found itself amidst the global economic recession, unable to employ all of its graduates. The company implemented an interviewprocess instead. “I was one of those offered a job, but itwas with Sasol Synfuels in Secunda, which I was less inclined to accept. Instead, I stayed on at Wits to complete a Master’s degree in the hope thatmy preferredoptionwouldopenup after an economic turnaround,” Fakir informs MechChem Africa . He went back to do a full time Masters degreeattheUniversityoftheWitwatersrand by dissertation and research. “My work was inspired by Professor Nicola Wagner, who isn’t a chemical engineer, but is considered a South African expert on fine coal petrogra- phy, a specialised branch of coal science that focuses on analysing coal using microscopy. The technique enables coal deposits to be categorised according to their age and gene- alogy. The composition, calorific value, ash content and a host of other properties can be accurately characterised, without the need to use formal ‘chemical’ analysis techniques,” Fakir explains. “I was co-supervised by Dr Shehzaad Kauchali, who headed up the Gasification Technology Research group at Wits. So my Masters was a synergistic blend of coal science and chemical engineering, which helped further expand my understanding of the inter-relatedness of the different fields of knowledge, and how they support each other,” he explains. Qasim Fakir’s MSc research involved coal gasification. “I used the distributed activa- tion energy model (DAEM) to understand the pyrolysis behaviour of high-ash content

“ A t my high school in Lenasia South, I always displayed a natural flair for mathematics andproblemsolving. Iwas lucky enough to have a passionate maths teacher who supportedme andwas first to adviseme to become an engineer. This was before I had any formal knowledge of what engineering was about, the different fields of engineer- ing, how they related to each other and what engineers in industry did,” Fakir begins. During an open day at the then RAU, now the University of Johannesburg (UJ), there was a Sasol Stand where bursary forms were being handed out. “I was with a group of friends just ‘checking the scene’ as I had already made up my mind that going to uni- versity might not be a reality for me. I took a form, though and completed it, selecting to study chemical engineering, still not knowing what it was really about,” he says.

Together with the management team of Saint-Gobain Gyproc, Qasim Fakir received the World Class Manufacturing (WCM) Bronze award in 2018 for Quality and Process Control, an award that lays a solid foundation for future investment within South Africa.

6 ¦ MechChem Africa • April 2019

⎪ SAIChE IChemE news ⎪

approaches to the tasks and problems that needed to be addressed: asking what we can do to eliminate defects, initiate improvement projects and identify, in advance, the benefits and consequences,” he reveals. He cites a success in the Domestos liquid bleach bottling line. “We had an issue with leaking bottles which, on investigation, was being caused by the relative orientation of the bottles just before the cap was screwed on. We modified the line alignment, put a new quality standard in place to manage the bottling machine and completely eliminated the problem,” he relates. Following four years as the quality engi- neer at Unilever, Fakir was ready for a new challenge and joined the US multinational, 3M, as its process and quality assurance (QA) manager. “I think there is natural linkbetween process control andproduct quality. Being re- sponsible for the implementationsideenables quality standards to become an intrinsic part of production,” he argues. Considered as one of the world’s most in- novative companies, 3M invented thePost-it- note. Fakirwas given responsibilityacrossfive separate 3Mbusinesses, which included their HealthCare,Consumer,Industrial,Electronics & Energy, and Safety & Graphics businesses. “I found myself looking at ways to reduce the waste losses during the production of Scotch-Bright ® washing up sponges, and improving the product performance of our FFP2-rated dust-masks to exceed SANS requirements. The sheer diversity of the role lent itself to my continued development and helpedmehonemymanagementandbusiness acumen skills,” he says. “I was also the first South African to re- ceive theGlobal QualityAchievement Award for 3M, at itsUS-basedheadquarters in2017,” he says excitedly. “It waswhile at 3Mthat I became involved with SAIChE IChemE, with a view to contrib- utingtothefutureofthechemicalengineering industry. I work predominantly in the manu- facturing space, which is less mainstream for most chemical engineers in South Africa. “The profession is ideal for those who are innovative and looking for solutions to the problems they see around them,” Fakir advises. He recently joined Saint-Gobain Gyproc as its senior process engineer, which involves similar but less complex responsibilities to the oneshehadat3M.“WesupplyGypsum-based products for the construction and retail sec- tors and I am responsible for the production site, looking after manufacturing processes, testing new processes and raising quality standards. “Mine is a challenging role, involving pro- cess and cost optimisation across the supply chain, while upscaling the production of new

and more sustainable modern products. Qasim Fakir was a member of the plant management team that contributed to the Brakpan plant achieving its World Class Manufacturing (WCM) Bronze award in2018 for Quality and Process Control, an award that lays a solid foundation for future invest- ment within South Africa. “As a profession, chemical engineering involves critical problem solving techniques that I apply on a daily basis: should we buy from local supplier? Should we change the formulation of ourmixture? Andwhat are the consequences of these decisions likely to be for our business, processes and products and, ultimately, our customers?” Chemical engineering enables profes- sionals to steer their career in many differ- ent directions. “I have been involved in the petrochemical field; fast moving consumer goods; automotive; healthcare; and now construction. The diversity of opportunity is endless and, for those who challenge the status quo , are self-starters and can come up with, and see solutions through, chemical engineering is a highly rewarding choice,” he concludes. q

coals, biomass andblends of coal andbiomass. This model used mathematical algorithms to characterise the pyrolysis behaviour of the fuels in an inert atmosphere to predict their decompositionproducts and the rateatwhich theseproductsdevolatiliseduringthethermal decomposition reaction. “The model was able to predict pyrolysis behaviours and products of high-ash South African coal and it was also extended to include biomass fuels. We tested blends of coal and biomass and compared the results to the values predicted by the model – and the correlation was excellent,” he informs MechChem Africa .. The dissertation was selected to be pre- sented at the prestigious Pittsburgh inter- national Coal Congress in 2010, but due to funding constraints, he was unable to attend. The published work, however, laid a good foundation for further work on a variety of combustion scenarios and was used as the basis for a PhD project looking at different types of coal and fuel sources. Sasol conducted interviews during 2009/2010andFakirwas againofferedapost at the Synfuels production site in Secunda. “I was alsooffered funding for aPhD, but having already spent six years studying, I was ready to work and earn money. I thus opted to part ways with Sasol and was recruited into a graduate recruitment programme atUnilever South Africa.” In2011, Fakir startedwork at theUnilever Washing Powder Plant in Boksburg as a pro- cess engineer with a focus on new product development. “I started out looking at taking products fromour research anddevelopment teams and upscaling production processes to make them viable,” he says, adding that this gave him the process innovation and new technology development opportunities that he had first seen at Sastech. “The job also involved a process optimi- sation element, reducing costs, using fewer resources, improving production and energy efficiencies and reducing environmental im- pacts,” he adds. Then, during a restructuring exercise at Unilever, a technical resource gapwas identi- fied in the quality department. “A quality en- gineer role was created, and I was appointed. Thiswas apivotal point inmy career. It opened my eyes to how the whole quality engineer- ing world works, from supplier management, through to the development of production cyclesand,viaqualitymanagementalltheway through to customer satisfaction. The whole value chain has to be aligned to deliver high quality products and services to consumers,” he points out. “Andwhile the scope of this newrolewent beyondtheboundsofpurechemicalengineer- ing, I was able to bring process methodology

SAIChE IChemE

SAIChE IChemE Board members: President: D Lokhat Past president: C Sheridan Honorary treasurer: L van Dyk Honorary secretary: EMObwaka EXCOmember: MHughes EXCOmember: JJ Scholtz Council member: D van Vuuren Council member: MChetty  Council member: HMazema Council member: K Naidoo Council member: P Cairns Council member: MMabaso Council member: C Sandrock Member (co-opted): NN Coni Member (co-opted): MD Heydenrych Contact details SAIChE PO Box 2125, North Riding, 2162 South Africa

Tel: +27 11 704 5915 Fax: +27 86 672 9430 email: saiche@mweb.co.za saiche@icheme.org website: www.saiche.co.za

April 2019 • MechChem Africa ¦ 7

The safe, reliable operation of tunnel boring equipment relies on the integrity of critical bearings and seals. This article from SKF describes the design considerations involved in arriving at suitable solutions. Bearing and seal design for tunnel boring machines

O nceconstructionstarts,there’sno going back. A tunnel boring ma- chine (TBM) is not equippedwith a reverse gear, so it is imperative that the machine is able to complete its job without suffering any significant mechanical failure en route. Where problems do occur, accessing the machine for repair can be a complex, costly and time-consuming project, especially if themain slewingbearing installed insidetheTBM’sgearboxisinvolved.Themain slewing bearing is the heart of the machine and, in case of failure, it cannot be replaced easily, potentially causing months of delays and cost overruns that could easily add up to millions of dollars. For design engineers, the challenge of delivering high levels of reliability and avail- ability are compounded by the extremely tough working conditions associated with tunnelling works. TBMs combine several highly undesirable operating conditions for key components, including slow rotating speeds, high static and shock loads, and a wet, dirty environment. Together, these characteristics are a recipe for accelerated wear and component damage. For decades, SKF has collaborated with major TBMmanufacturers to develop robust bearing, sealing and lubrication solutions that can meet the requirements of the most demanding tunnelling projects in the world. Describedherearesomeofthekeychallenges associated with the design, operation and maintenance of these components, and the solutions available to address them. Cutting disc bearings A large TBM uses a large number of cutting discs, each rotating on a pair of taper roller bearings (TRB). In operation, these bearings are subject to high transient loads, which rise dramatically as the disc is forced into the rock, and are suddenly released as the material fractures. The rotating speed of the disc depends on its position on the cut- ter head, but it is typically in the range of 10 to 20 rpm. The use of ever-larger TBMs has led to a commensurate increase in cutter disc diameter, which has grown from the standard 13 inches (330mm) some years ago to 17, or even 19 inches (432 or 483 mm),

on the largest modern machines. The location of cutting disc TRBsmakes it very likely that bearing surfaces will become contaminated during operation. This, com- bined with the presence of extreme shock loads means bearing manufacturers must

to prevent bursting in failure conditions. Testing the cutting disc bearing pres- ents another challenge for manufac- turers. There is no test rig available that can adequately reproduce the rigoursofreal-worldoperation,and operating conditions can vary sig- nificantly from project to project. As a result, bearing design engi- neers must rely on a combination of experience and computer simula- tion when evaluating a new design. The conditionof bearings removed from worn cutting discs can also pro- vide useful information about their operating conditions. Expert analysis of wear and damage to bearing surfaces can reveal opportunities tomodify operation and maintenance procedures to maximise bear- ing life. In cases where projects have faced unexpectedly challenging ground conditions, SKF engineering teams have been able to use insights gained from damaged bearings to produce customised solutions designed to offer improved performance. Since disc replacement operations are conducted underground, they must be as straightforward as possible, and require minimal use of time, manpower and specialist tools.Thereliableoperationofthetaperroller bearings inside the discs, however, relies on an appropriate level of pre-load, which must be set by the maintenance team when the bearings are mounted. In practice, operators have limited ability toassess bearingpreload in thefieldandmust rely on the torque measured on the arrange- ment during assembly. To assist operators in this critical assembly step, the TRBs used in cutting discs are manufactured to tight dimensional tolerances, thereby ensuring the closest possible correlation between mounting torque and preload. Other factors come in to play as well, however, including

TBMs use a large number of cutting discs that are subject to high transient loads. Each disc rotates on a pair of taper roller bearings (TRB).

design the bearings to cope with uneven loading and highly localised forces on roll- ers and raceway surfaces. At the same time, considerationmust be given to thenatureof a prematurebearing failure should it occur. The priority here is to avoid complete fracture of a raceway, which would lead to blocking of a disc leading to damage of multiple discs. Building a bearing that can handle this environment requires careful attention to geometry, material selection and surface treatment approach. Design engineers need to make use of proprietary finite element analysis tools to optimise key bearing design andmanufacturing parameters, todeliver the best combination of characteristics. Small adjustments to raceway geometry can have a big impact on the bearing’s ability to cope with irregular loads. For example, the use of precisely controlled case-hardening of raceways provides rolling surfaces with suf- ficient hardness while retaining a tough core

8 ¦ MechChem Africa • April 2019

⎪ Power transmission, bearings, bushes and seals ⎪

tiple objectives: retaining lubricant within the bearing assembly, keeping out water, mud and debris and accommodating the sig- nificant misalignment that can occur during operation. The sealmust be able to fulfil these duties for the full duration of the project, even while subject to continual abrasion by rock particles. To achieve the desired levels of per- formance, several lip seals in series, with lubrication in between them, are commonly used. SKF’s TBM seals are designed by utilising FEA to consider all load cases such as misalignments, pressurisation, grease flushing and eveninstallationbehaviour.Tosimplify assembly processes, and to facilitate on-site replacement of seals, SKF has developed a specialised welding pro- cess using compact, handheld equip- ment that allows engineers to operate in confined spaces. This process allows main seals to be installed without the need to remove the cutting head, reduc- ing downtime significantly. In addition to the highly specialised com- ponents developed specifically for TBM applications, SKF provides awide range of other components, systems and solutions for machine manufacturers. These include standard bearings and seals used in screw conveyor drives, erector bearings and other ancillary equipment, alongwith sophisticated centralised lubricationsystems that can inject oil or grease directly into bearings in precise quantities to ensure optimum lubrication with minimal wastage or environmental contamination. Remanufacturing As operators look to maximise the lifetime value of their assets, they are increasingly looking for opportunities to re-use complete TBMs and key components on multiple proj- ects. Component re-use can result in lower costs, less environmental impact and smaller parts inventories. To help manufacturers achieve their ob- jectives, remanufacturing of TBM bearings is a good option. Used bearings are returned to specialist facilities or directly to cus- tomer sites around theworld, where they are cleaned, disassembled and inspected. Worn parts are replaced or reconditioned and the completedunit is inspected, documented and returned ready for reinstallation. SKF has beenworkingwith leading tunnel boring machine OEMs since the early 1990s and its proven solutions continue to enable improved machine reliability, faster project times and lower costs of ownership. q Other bearings and lubrication solutions

Safe, reliable operation of tunnel boring machines (TBM) relies on the integrity of critical bearings and seals. the condition and lubrication of mounting hardware, so careful inspection of compo- nents and adherence to standard mounting protocols are essential. Bearing suppliers can also provide support to operators in the development of appropriate disc bearing replacement procedures and the training of maintenance personnel. Slewing bearings While all cutting disc bearings use a broadly similardesign,TBMmanufacturersaresetting higher and differing demands on the design of the main slewing bearing. This is the most critical bearing of the TBM and is the link be- tween the pinion drives and the cutter head, while also taking over the huge loads induced during tunnelling operations. Slewing bearing assemblies can range in size from less than 2.0 m in diameter for micro-tunnelling ap- plications up tomore than 8m for the largest tunnellingmachines. Manufacturersmay use different bearing arrangements depending on the size of the machine, the anticipated ground conditions and the overall machine architecture. As a result, a slewing bearing is always a highly customised design, created in collabo- rationwiththeOEMandbearingsupplier.SKF has developed specialised design and optimi- sation software for suchprojects, allowing the modelling and simulationof complete slewing bearingassemblies including rollingelements, cages, raceways, drive gears andmounting ar- rangements. Consequently, accurate calcula- tions of bearing and gear lifetime under given load conditions can be determined. Special solutions incorporated into TBM slewing bearing designs can include spring-loaded racewaydesigns to reduce shock loads inhard rock applications. The large size of TBM slewing bearings presents challenges for transportation, as- sembly andmaintenance. DependingonOEM

The critical slewing bearing is

the link between the pinion drives and the cutter head, while also taking over the huge loads induced during tunnelling operations. requirements, slewing bearings can be sup- plied as single parts or fully assembled units that include the sealing system. In some cases, bearings may be constructed in segments to facilitatetransportation,mountingorreplace- ment in case of unforeseen events that affect the machine. In addition to the main slewing bearings, therearealso special ranges of slew- ing bearings for screwconveyors and erector systems on the market. Seals Slewing bearings rely on proper lubrication and ingress protection to survive. Thismeans that the seals used to protect these bearings against the harsh environment in tunnel bor- ing are a project-critical component. Like the slewing bearing assemblies themselves, sealing solutions for TBM main bearings need to be optimised to suit the needs of the typical applications as well as customised for projects with even more ex- treme conditions. SKF retains full control of the seal design and manufacturing process, formulating its own proprietary materials and using in-housemanufacturing processes to ensure precise control of finished seal geometry, regardless of the size of the ma- chine involved. Slewing bearing seals must achieve mul-

April 2019 • MechChem Africa ¦ 9

Flexibility, innovation and tailormade drive solutions

MechChem Africa presents some recent success stories from SEW EURODRIVE that demonstrate the flexible use of its drive technology in satisfying a wide range of customer-specified outcomes.

service and technical back-up,” Weinmann comments. “It is important to note that we do not simply supply products, but look closely at the holistic application itself.” Due to the fact that this massive order had to be customised, an important part of the value-added service offering was over- seeing that the required specifications were met, keeping in mind the strict delivery date. This was essential in giving the client peace of mind. “We like to be on-site during this critical phase of any project in order to ensure that everything is according to specification and installed correctly. For example, we double check the oil levels and the alignment of the units, and are also present at the first cold start-up,” Weinmann notes. Critical to the success of this project was the close working relationship forged with the project house, which resulted in SEW- EURODRIVEbeingaffordedanextended lead time. “This not only allowed us to iron out all of the technical specifications in advance, but was of great benefit to our sub-suppliers as well,” says Farthing.

Head of exports, Marcio Sicchiero.

Film Riggers help French Spiderman Specialist rigging company Film Riggers was recently called upon to ensure the safety of Alain Robert, also known as the French Spiderman, while scaling a skyscraper in cen- tral Johannesburg for an advertisement for an international tyre manufacturer. The specialist rigging company is a long- time user of automation and mechatronics technology from SEW-EURODRIVE, in addi- tion to deploying its drives for its customised winches. It was approached by a production company to execute the logistics and safety requirements for the advertisement. The idea was to haveRobert climb the buildingwhile it was raining, as a metaphor for the extra grip provided by the tyres being showcased. Partner Graham Terrell, who established

MAXOLUTION engineer, Dylan Enslin.

A s part of itswell establishedmining offering, the Projects Department of SEW-EURODRIVE, under the directionof project sales represen- tatives, BrettWeinmann and Bruce Farthing, has delivered a complete drive package for a newmineintheMpumalangacoalfields,which has standardisedondrives fromSEW-EURO­ DRIVE for its entire conveyor-belt system. This entailed a 27-unit order in the form of a simple ‘bolt-on’ solution for the coal mine’s conveyor-belt system, which were as- sembled at the OEM’s Nelspruit facility and transporteddirectly to siteearly this year. The project scope included the drives themselves, gearboxes, base plates, guards and, in one instance, an ancillary cooler. Such was the success of the work under- taken that SEW-EURODRIVE has subse- quently clinched another three cross-border projects with the same client, assisting in expanding its footprint in the African mining industry. Weinmann explains that the long-term aim of the Projects department is to estab- lish longstanding relationships with project houses, in particular, who put their designs out to competitive tender. Thereafter it is the responsibility of Farthing, a qualified mechanical engineer, to come up with a solu- tion best-suited for the application in hand, which is subsequently presented to the client for approval. “Our team is very dynamic in devising the best solutions for our clients. We really go out of our way to offer the best customer

10 ¦ MechChem Africa • April 2019

⎪ Power transmission, bearings, bushes and seals ⎪

Film Riggers with Alard Hüfner in 2012, ex- plains that Robert had two ropes attached to a harness, controlled by SEW-EURODRIVE driveswithacustomprogrambasedontorque control to delay the climber. The winches devised by Film Riggers use the MOVIDRIVE ® drive inverter from SEW- EURODRIVE, which includes the IPOSplus ® integrated positioning and sequence control system as standard. The drive inverters have a wide power range, large overload capacity, and a modular design. In addition, they fa- cilitate unrestricted application of AC drives, featuring the most modern digital inverter technology, this according toMAXOLUTION ® Engineer, Dylan Enslin. For this particular project, Film Riggers usedCM112 synchronous servomotors from SEW-EURODRIVE. Two 11 kW drives were used to secure the climber, and a 30 kWdrive for the accompanying camera system. Terrell was given access to the OEM’s electronicsworkshoptoconfigureaminiature set-up of the system, based on a 0.55 kW MOVIDRIVE drive inverter. This allowed for more controlled and refined testing, allowing Terrell to scale up the solution to the specific requirements of the project. Commenting on the challenges posed by the project, Hüfner points out that Film Riggers had the dual responsibility of winch- ing the camera platformup anddown, in addi- tion to securing Robert, and ensuring his own safety during the filming process. “The ideawas for the camera to be seen to be almost in pursuit of him, then tilting as it

went past, while trackinghim. Therewere cer- tain changes made at the last minute, which meant we had to adjust our programming in order to cater for the new reference points needed for our rigging,” Terrell elaborates. “This is a unique application of theMOVI­ DRIVEdriveinvertertechnologyandanexcel- lent example of the flexibility and innovation we canprovide to specific customers, offering tailormade solutions based on the latest de- velopments,” Enslin explains. A major cement producer in Zambia has also invested significantly in a comprehensive stockholding of critical spare units to prevent any costly downtime and subsequent loss of productivity. The multimillion-rand order for SEW-EURODRIVE equipment consists of 40 units, including geared motors, planetary units, and Industrial Gear (IG) units, ranging from 7.5 kW to 250 kW. A total of 15 cus- tomised IG units are being supplied by SEW- EURODRIVEof Finland, while other units are also being sourced fromGermany. “This is testament to the internationalisa- tionofSEW-EURODRIVE,whichcancallonits extensive global capabilities in order tomeet the specific requirements of major clients in the required timeframe,” says headof Exports, Marcio Sicchiero, adding: “This long-standing client has enjoyed a close relationshipwith us for the past three years.” Because of the size and quantity of the order, the products are being dispatched to Cement producer stocks up on critical spares.

Zambia from the SEW-EURODRIVE head of- fice in Johannesburg in six different batches, withdifferent lead times, in order to facilitate transportation and logistics. The OEM is providing technical support and assistance directly from South Africa, with export sales representative, Philip Steyn, already having travelled to site five times. The back-up support offered on this par- ticular project has even included assistance with correct storage procedures. Being criti- calspares,theseproductswillnotbedeployed in the plant straightaway, and therefore have to be stored correctly to avoid any issues when they are required. “The client has opted for the critical spares stockholding due to the impact that any downtime has on productivity,” Sicchiero explains. This is a proactive approach to maintenance that takes advantage of the user-friendliness and simple installation of the SEW-EURODRIVE products. Commenting on the current state of the cement industry in Africa, Sicchiero points outthatmajorproducerssuchasthisZambian client are expanding aggressively on the con- tinent, so as to be less dependent on South African markets. “While our involvement with the cement industry in Africa is quite extensive, it does tendtovaryfromcountrytocountry,andeven companytocompany.However,thereremains significant scope for us to expand in this sec- tor, especially with regard to standardisation of entire plants and the provision of critical spares,” Sicchiero suggests. q

Left: The 27-unit complete drive package order from SEW-EURODRIVE was assembled at the Nelspruit facility and consisted of the drives, gearboxes, base plates, and guards. Below: SEW-EURODRIVE’s bolt-on solution for the conveyor system.

April 2019 • MechChem Africa ¦ 11

⎪ Power transmission, bearings, bushes and seals ⎪

BMG has extended its range of Tsubaki chain wear indicators, with the addition of the recently-launched large size gauges. Regular wear checks, better maintenance management

“ T subaki chain wear indicators enable plant andmachinery engineers to accurately measure roller chain conditions and to determine critical wear in a simple operation,” says CarloBeukes, BMG’s business unitmanager: power trans- mission. “These robust gauges are valuable tools to ensuremachinery ismaintained inpristine conditionand forminimisingunexpectedchain failures that lead to costly production downtime. “We recommend that chain wear indictors are used as part of the regular maintenance schedule of a machine or production line. By regularly checking and replacing chains before they reach 1.5% elon- gation, shock loads are prevented and sprocket wear is significantly hindered,” Beukes. The corrosion-resistant gauges –manufactured to stringent quality specifications – have one end shaped tomount over a roller, while the tip of the other end indicates the degree of wear by highlighting the total elongation over a number of links. Since the chain might wear unevenly, the manufacturer stresses the importance of measuring on several points of the chain. “Correct chaincare involvesmonitoringchainwear,whichcancause a loss of tension, and thus reduced transmission efficiency. Chainwear also affects the alignment accuracy of the drive, which increases noise and vibration levels. If wear is allowed to increase to a critical point, the chainwill begin riding and jumping on the sprockets, which causes shock loads, which in turn further accelerate wear.” These problems are avoidedwith the regular use of BMG’s Tsubaki

Tsubaki chain wear indicators enable plant and machinery engineers to accurately measure

chain wear indicators, which play an important role in maintenance programmes, to ensure optimumefficiency of the overall drive system. The complete range of Tsubaki power transmission components is available fromBMG’snational branchnetwork,whichoffers a technical advisory and 24-hour back-up service. The new Tsubaki BS large size indicators are available in sizes RS20B to RS48B while ANSI large size indicators cover sizes RS100 toRS240. These complement the existingBS sets, which are usedwith sizes RF06B to RS16B and ANSI sets for sizes RS35 to RS80. To meet market demand, thenewlarge size indicators areavailableas individual items, rather than as part of a set. q roller chain condition and to determine critical wear, in one simple operation. BMG has extended its range of Tsubaki chain wear indicators to include Tsubaki’s recently-launched large size gauges.

April 2019 • MechChem Africa ¦ 13